The present invention relates to the area of LED lightling technology, and in particular relates to methods and an apparatus for power supply for driving an LED light system with a TRIAC (Triode for Alternating Current) dimmer.
LED (light-emitting diode) lighting systems as a fourth-generation light source have gradually replaced conventional fluorescent and incandescent lighting in a wide range of applications in various fields. In comparison with conventional lighting technologies, LED lamps have many advantages, for example, high light efficiency, long life, low power consumption, and so on. However, there are still challenges in using LED lamps to replace conventional light source. For example, conventional light systems often include TRIAC dimmers for adjusting brightness of light output. When an LED lamp is used to replace the fluorescent or incandescent lamp, the LED lamp often suffers from flickers. It can also be difficult to achieve a wide range of dimming control.
As is known in the art, a TRIAC is a bidirectional semiconductor switching device that allows large current to flow through in either direction when triggered by a positive or negative current at its gate electrode. Once triggered, the device continues to conduct until the current drops below a certain threshold, called the holding current.
Thus, for a TRIAC switch to work properly, it needs a trigger current IL and a holding current Iholding. The trigger current is a minimum current of the trigger signal at the gate to cause a current to flow in the TRIAC, and the holding current is the minimum current to maintain conduction after the TRIAC is triggered. Once the current flowing through the TRIAC is not sufficient maintain the holding current, the TRIAC will turn off and may cause TRIAC to be triggered again. As a result, light flickering often occurs.
Therefore, there is a need for improved power supply for driving an LED light source and maintain compatibility with conventional TRIAC dimmers.